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fma(3) — Linux manual page

fma(3)                   Library Functions Manualfma(3)

NAME        top

       fma, fmaf, fmal - floating-point multiply and add

LIBRARY        top

       Math library (libm,-lm)

SYNOPSIS        top

#include <math.h>double fma(doublex, doubley, doublez);float fmaf(floatx, floaty, floatz);long double fmal(long doublex, long doubley, long doublez);   Feature Test Macro Requirements for glibc (seefeature_test_macros(7)):fma(),fmaf(),fmal():           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L

DESCRIPTION        top

       These functions computex *y +z.  The result is rounded as one       ternary operation according to the current rounding mode (seefenv(3)).

RETURN VALUE        top

       These functions return the value ofx *y +z, rounded as one       ternary operation.       Ifx ory is a NaN, a NaN is returned.       Ifx timesy is an exact infinity, andz is an infinity with the       opposite sign, a domain error occurs, and a NaN is returned.       If one ofx ory is an infinity, the other is 0, andz is not a       NaN, a domain error occurs, and a NaN is returned.       If one ofx ory is an infinity, and the other is 0, andz is a       NaN, a domain error occurs, and a NaN is returned.       Ifx timesy is not an infinity times zero (or vice versa), andz       is a NaN, a NaN is returned.       If the result overflows, a range error occurs, and an infinity       with the correct sign is returned.       If the result underflows, a range error occurs, and a signed 0 is       returned.

ERRORS        top

       Seemath_error(7) for information on how to determine whether an       error has occurred when calling these functions.       The following errors can occur:       Domain error:x * y + z, orx * y is invalid andz is not a NaN              An invalid floating-point exception (FE_INVALID) is raised.       Range error: result overflow              An overflow floating-point exception (FE_OVERFLOW) is              raised.       Range error: result underflow              An underflow floating-point exception (FE_UNDERFLOW) is              raised.       These functions do not seterrno.

ATTRIBUTES        top

       For an explanation of the terms used in this section, seeattributes(7).       ┌──────────────────────────────────────┬───────────────┬─────────┐       │Interface│Attribute│Value│       ├──────────────────────────────────────┼───────────────┼─────────┤       │fma(),fmaf(),fmal()                │ Thread safety │ MT-Safe │       └──────────────────────────────────────┴───────────────┴─────────┘

STANDARDS        top

       C11, POSIX.1-2008.

HISTORY        top

       glibc 2.1.  C99, POSIX.1-2001.

SEE ALSO        top

remainder(3),remquo(3)

COLOPHON        top

       This page is part of theman-pages (Linux kernel and C library       user-space interface documentation) project.  Information about       the project can be found at        ⟨https://www.kernel.org/doc/man-pages/⟩.  If you have a bug report       for this manual page, see       ⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.       This page was obtained from the tarball man-pages-6.15.tar.gz       fetched from       ⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on       2025-08-11.  If you discover any rendering problems in this HTML       version of the page, or you believe there is a better or more up-       to-date source for the page, or you have corrections or       improvements to the information in this COLOPHON (which isnot       part of the original manual page), send a mail to       man-pages@man7.orgLinux man-pages 6.15            2025-05-17fma(3)

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